1. Field of the Invention
This invention relates to a wireless communication field, and particularly to a communication processing method, an apparatus and a gateway device.
2. Description of the Prior Art
Currently, TCP (Transmission Control Protocol) is a connection oriented (connection directed) and reliable transport layer communication protocol based on a byte flow, which is defined by RFC 793 of IETF. The TCP is widely applied in data transmission in Internet for users.
According to the TCP, an end-to-end connection between a wireless terminal and a remote server may be established. At two ends of the TCP, respective protocols run in order to ensure that the user data can be transmitted sequentially and correctly.
At the same time, the congestion control mechanism included in the TCP may dynamically adjust a size of the transmission window at the transmitting side so as to prevent the transmitting side from transmitting data without limit, which may result in the network congestion. According to the congestion control mechanism of TCP, whether a packet is lost has been taken as an indicator of whether the network congestion occurs. According to the TCP, when an ACK packet having a same sequence number may be received continuously for several times (for example, 3 times), the size of the transmission window will be reduced by a half so as to reduce the transmission rate and to prevent the congestion.
However, at the beginning of designing the TCP, the main application environment is supposed to be for a wired network and the properties for wireless environment are less concerned. In the wired network, data packet loss due to transmission itself seldom happens (for example, the packet loss rate is less than 10−6). Therefore, according to the congestion control mechanism of the TCP, it is reasonable to assume that the data packet loss is due to congestion and accordingly the transmission rate is reduced to prevent such congestion. However, in the wireless environment, the data packet loss due to the wireless transmission itself cannot be ignored, such as the wireless signal loss, channel fading and various interference shields. According to the congestion control mechanism of the TCP, the packet loss due to the wireless transmission will be wrongly regarded as the packet loss due to the congestion and the transmission rate will be unnecessarily reduced, which may result in the reduction of the transmission rate.
On the other hand, the transmission delay of the wired network is comparatively short and does not fluctuate a lot, while the transmission delay of the wireless network (for example, cellular network) is comparatively long and fluctuates a lot, which disadvantageously influences the performance of the TCP.
According to conventional optimization solutions for using the TCP in the wireless network, it is assumed that the wireless terminal is coupled to the wired network through certain wireless network (for example cellular network or WLAN) and then is coupled to the server in the Internet. The two ends of the TCP are established on the wireless terminal and the server in the Internet respectively. Since the TCP connection is realized through the wireless network, the high data packet loss and delay characteristics of the wireless network may influence the performance of the TCP connection adversely.
As described above, according to the conventional solution, it is assumed that the TCP connection accesses the wired network and Internet through a wireless network. However, with the development of the technologies, the wireless terminal may access Internet through the heterogeneous network and the conventional TCP optimization solutions cannot be adapted to the heterogeneous network.